Conventionally, a refrigerating apparatus for cooling an inside of a compartment of, e.g., a refrigerator or a freezer has been known.
For example, Patent Document 1 discloses a refrigerating apparatus for cooling an inside of a compartment of a container used for, e.g., marine transportation. The refrigerating apparatus includes a refrigerant circuit in which a compressor, a condenser, an expansion valve, and a cooling heat exchanger (evaporator) are connected together. In the refrigerant circuit of the refrigerating apparatus, refrigerant circulates to perform a vapor compression refrigeration cycle. As a result, refrigerant flowing through the cooling heat exchanger is evaporated by absorbing heat from in-compartment air, thereby cooling the in-compartment air. In the refrigerating apparatus, a freezing operation in which in-compartment air is set to have a temperature lower than zero degrees Celsius to freeze stored products in the container and a refrigerating operation in which in-compartment air is set to have a temperature higher than zero degrees Celsius to refrigerate the stored produces in the container are allowed.
In the refrigerating apparatus of this type, since in-compartment air has the temperature lower than zero degrees Celsius in the freezing operation, moisture contained in the in-compartment air is adhered to a surface of the cooling heat exchanger as frost. As an amount of frost adhered to the cooling heat exchanger is increased, a cooling capacity is reduced. Thus, a defrosting operation is performed in order to avoid such reduction of the cooling capacity. In a refrigerating apparatus for a marine container, a refrigerant circulation cycle (referred to as a “hot gas defrosting cycle” or simply referred to as a “defrosting cycle”) in which discharge refrigerant gas from a compressor is sent to an evaporator and is returned to the compressor has been typically employed, and frost adhered to a cooling heat exchanger is melted by heat of the discharge refrigerant gas.